DESCRIPTION: This SBIR application involves development of a kit to allow screening of the most common cystic fibrosis mutation (the three base pair deletion at codon 508) in a clinical setting. This second tier screening will be performed after or in conjunction with the current immunoreactive trypsin test. The principal investigator, who has wide experience in developing screening tests, will collaborate with one of the scientists who initially identified the cystic fibrosis gene eight years ago to develop a DNA-based assay kit that is intended to be robust and easy to use. The application describes the need for such a kit, that there is not one currently available and that very early testing can have a significant outcome for the health of the young patient.